Samsung's smartphone business has spearheaded the company's growth in recent years, but its shares took a hit after brokerages downgraded its outlook based on the early performance of the Samsung Galaxy S4.

"The slowdown in its handset business appears to be worse than expected and the disappointing result simply reinforces the market view that Samsung's smartphone growth momentum is slowing," said Lee Sei-chul, an analyst at Seoul-based Meritz Securities.